ATOR (Arc-Team Open Research).
The blog spreads tests, problems and results of Arc-Team research in archaeology, following the guidelines of the OpArc (Open Archaeology) project.

Monday, 30 January 2017

Digitizing the excavation

The 21st Conference on Cultural Heritage and NEW Technologies (CHNT 21, 2016) took place in Vienna the first week of November 2016. In that occasion we gave a presentation entitled "Digitizing the excavation. Toward a real-time documentation and analysis of the archaeological record". Today I found the time to publish it in our blog, to share our research regarding this topic and in particular some interesting projects of "archeorobotics" we are working on.

Here below you can see the video of the presentation, done like always with the open source software impress.js and Strut...

... and here is a short description of each slide:

SLIDE 1

The title (strictly related with Digital Archaeology in general)

SLIDE 2

A short presentation of Arc-Team

SLIDE 3

All the work has been done thanks to Free/Libre and Open Source Software. In order to keep going on with our research regarding archaeological methodology we need the source code!

SLIDE 4

The fundamental schema of the archaeological cognitive process elaborated by G. Leonardi in 1982. The schema shows the progressive reduction of the informations regarding human actions before and during the archaeological excavation (Human activities --> Traces on the soil --> Natural and anthropological degradation of the record --> archaeological excavation --> archaeological documentation) until the interpretative knowledge starts recover information during the post-excavation stage (with analitical data interpretation and reconstructive hypothesis)

SLIDE 5

A practical example of the schema from the site of Torre dei Sicconi in Italy (a medieval castle):

1. Human activities (summarized in the building of the castle, the medieval battle and the destruction of the main structure and the controlled explosion during the Great War)

2. Traces on the soil (summarized in the evidences of the battle, of the controlled explosion and of recent agrarian activities, while just negative layers were found regarding the construction of the structure)

3. Natural and anthropological degradation (summarized in the battle, the explosion, the agrarian activities and the normal natural dynamics)

4. Archaeological excavation (the most destructive investigation: in Torre dei Sicconi all the layers concerning the tower and the main central building has been removed by this activity)

5. The importance of archaeological documentation comes from distructive analysis (excavation). Being a long term project, Torre dei Sicconi was documented both with traditional and digital methodology

6. Data analysis. During this stage our knowledge of the site started to grow again. In this case both archaeological and historical techniques have been used

7. Reconstructive hypotheses represent the maximum increase of our (interpretative) knowledge of the site. For Torre dei Sicconi this stage has been achieved just for the central part of the castle (tower and main building)

SLIDE 6

The archaeological excavation is the most critical (destructive) stage of our knowledge regarding a site.

2. on-site direct observation for a better interpretation, avoiding at the same time any kind of data selection

3. moving the lab into the field (chemical and physical analyses)

SLIDE 8

A milestone of our research: in 2006 the development of the "Metodo Aramus" gave us a better (more precise and accurate), faster and corect (equalized) 2D digital documentation with FLOSS.

SLIDE 9

Another milestone. Between 2008 and 2009 the migration from pure photogrammetric software to SfM and MVSR methods (through the development of a GUI for +Pierre Moulon's application Python Photogrammetry Suite) gave us better and faster 3D digital documentation

SLIDE 10

Even today we still use a combination of 2D and 3D techniques to meet different requirements of various archaeological projects

SLIDE 11

2D digital documentation through GIS is fast enough for on site interpretation during emergency excavation

SLIDE 12

A software like +QGIS allows a direct interpretation on the field without the necessity of long post-rpocessing

SLIDE 13

3D documentation gives better results, but needs longer processing time (even if it does not need long data acquisition on the field, which is always performed)

SLIDE 14

We achieved (a lower quality) 3D data acquisition which has the fundamental characteristic of being real-time, thanks to open hardware (archeorobotics)

SLIDE 15

Our experience in archeorobotics dates back to 2006 with our first prototype of UAV, which could be use professionally just in 2008.

SLIDE 16

Currently or archeorobotics research regards our last prototype of Archeodrone (a UAV specifically designed for aerial archaeology)...

SLIDE 17

... some CNC machines and, above all, the Fa)(a 3D, a 3D open hardware printer which without any kind of modifications was able to satisfy our archaeological needs (like 3D printing casts of unique finds or exctract and print DICOM data form x-ray CT scan)...

SLIDE 18

... and the ArcheoROV, the open hardware Remotely underwater Operated Vehicle which we developed with the +Witlab Fablab

SLIDE 19

Some pictures of the first test of the ArcheoROV

SLIDE 20

A first step into 3D real-time documentation through SLAM (Simultaneous Localization and Mapping) techniques has been done with the open source ROS (Robot Operating System) and RTAB-Map via Kinect...

SLIDE 21

... and tested for 3D real-time documentation in wooden areas (where SfM and MVSR or laserscab would have been too slow), reaching in almost one hour of work a model (with real dimension) of 75000 points.

SLIDE 22

A benefit of archaeorobotic system like these (which are ROS capable) is the possibility to change the sensor in order to adapt the hardware to different situation, using monocular or stereo cameras (for odometry) as well as LIDAR or SONAR devices.

SLIDE 23

Another benefit is the wide range of possibilities offered by the different open source software (e.g. RTAB-Map, LSD-SLAM, REMODE, Cartographer, ecc...)

SLIDE 24

Currently the precision/accuracy level of a real-time 3D archaeological documentation cannot be compared with the results achieved with post-processing through traditional SfM - MVSR systems, but there are good prospects for improvement.

SLIDE 25

Nowadays, basing on our professional experience, the best use of such devices seems to be during extreme operations, such as high mountain archaeology, glacial archaeology, underwater archaeology or speleoarchaeology

SLIDE 26

Another important step to improve the reaction time of professional archaeology, in order to avoid errors during the critical stage of the excavation, is the possibility to perform some basic archaeometrical analyses (chemical and physical) directly on the field.

SLIDE 27

Considering the composition of any archaeological layer based on two different elements, the skeleton (macroscopic) and the fine earth (microscopic), it is obvious that different analyses can be performed in different work environment.

SLIDE 28

For instance, in the case of the skeleton, a fast petrografic (ontoscopic) analysis can be easily performed directly on the field (defining allogeneic elements), while further (more specific) investigations need an equipped laboratory.

SLIDE 29

Also in the case of fine earth, some raw descriptive analyses can be performed on the field, while laboratory investigation can reach very detailed results (e.g. with the Scanning Electron Microscope).

SLIDE 30

The field analysis of the fine earth is more problematic (compared with the skeleton) the most common test (e.g. the Soil texture by feel) are anametric and subjective

SLIDE 31

For this reason, archaeometric test are the better choice (e.g the sedimentation test)

SLIDE 32

The sedimentation test on the field can be improved with basic physical analysis (e.g. considering the Stoke's Law in order to define sand, silt and clay by the tme they need to sediment)

SLIDE 33

Another implementation on the field for the sedimentation test is the possibility to directly store the data into a PostreSQL/PostGIS database (through some specific fields of the archaeological recording sheet), using the open source application geTTexture.

SLIDE 34

An example of the use of geTTexture

SLIDE 35

Other archaeometric test which are simple to perform directly during the excavation are based on basic chemical analyses, and specifically with the quantification of compounds like phosphates or nitrates.

SLIDE 36

Moreover, with some simple workarounds, it is possible to turn anametric (boolean) analyses of carbonates or organic substances, into metric (quantitative) observations.

SLIDE 37

The Archaeological excavation is a destructive process, subject to fatal (not reversible) errors. Moreover the reduced time and budget in professional and emergency archaeology increase stress conditions during decision making stages.
Real-time 3D mapping can speed up data interpretation, avoiding data selection on the field, while on-site chemical and physical analyses (geoarchaeology and archaeometry) can define a better (data-driven) digging strategy.